As the latest standard for cellular telecommunication systems, LTE (Long Term Evolution) system is ambitiously intended to provide mobile users with a much higher data rate than before, in the order of 100 Mbps via the air, which is the data rate of one cable connection in the early days. Furthermore, to be able to utilize the limited radio resources more efficiently, the radio resources should be divided into a smaller unit that can be assigned to one user. OFDM (Orthogonal Frequency Division Multiplex) is perfectly fit for those purposes by sharing all the radio resources at both frequency domain and time domain. Thus OFDMA is directly accepted for the downlink in LTE. And uplink SC-FDMA (Single Carrier Frequency Division Multiplex Access) is actually an DFT (Discrete Fourier Transform) spread OFDM.
Compared with the previous cellular telecommunication systems, such as WCDMA (Wide-band Code Division Multiple Access), LTE system reduces the overhead for the physical control signalling by discarding any dedication physical control channel and fast scheduling the control resources. That means, all of the defined physical control channels are shared by all of the users in one cell via fast scheduling by the scheduler. This also fits the bursty data transmission as well. And of course, there are new challenges to design the physical control channel receivers. According to the current LTE standard, the physical control channel in uplink is called PUCCH (Physical Uplink Control Channel). So, the new challenges are to design PUCCH receivers.